PHOENIX — Presidential hopefuls testing the waters at a tea party convention Saturday said the grass-roots movement will play a key role in 2012 elections.

The tea parties “are going to have a lot to say about who the nominee is in 2012,” former Minnesota Gov. Tim Pawlenty told Roll Call.

He was one of three potential Republican candidates who spoke at the Tea Party Patriots policy summit. The other two were Rep. Ron Paul (Texas) and businessman Herman Cain. All three received standing ovations from the room of about 2,000 conservative activists.

When asked why more potential candidates did not attend the conference, Pawlenty said, “There’s not a lack of people running around the country giving speeches, so I’m not sure why they are not here.”

The former governor courted the tea parties by proposing a simpler tax system and the repeal of President Barack Obama’s health care law, touting spending cuts he made in Minnesota and giving his support to a balanced budget constitutional amendment.

Pawlenty did get some pushback during his speech when he said, “I’m not one who questions the existence of the president’s birth certificate,” and several audience members shouted back, “I am.”

Paul said he is still “fifty-fifty” about whether he will run in 2012 and said his popularity at the conference could influence the decision. The tea party group plans to hold a presidential straw poll on Sunday.

“If I am here and got a very, very poor reception, that could push me away from [running]. If I have a very good reception at a meeting like today, that would maybe encourage me but it won’t make up my mind,” Paul told reporters. “Because I know politics is a lot more complicated than that.”

Paul argued that his libertarian views make him a natural fit for the tea parties, but his interest in cutting military spending and opposition to real ID bills to address illegal immigration could hurt him.

“I’m for strong national defense and cutting militarism that doesn’t support defense. I think when [the tea parties] sort that out, they’ll understand a little better,” he said.

On requiring citizens to carry identification to curb illegal immigration, Paul added, “What I’ve cautioned our supporters that want to enforce the immigration laws is not to invite something that will backfire on them.”

It’s unclear whether the tea parties would support his view on either issue, but Paul did receive applause for his fiscal views — including eliminating the Federal Reserve system and the federal income tax.

Unlike fellow Texas Republican Joe Barton, who was shot down at the convention when he touted the House’s proposal to make $60 billion in budget cuts, Paul welcomed tea party dissatisfaction with his party’s progress.

“I don’t think they’re upset enough. I think they need to be a lot more upset,” he said.